Now that Salsa is in beta, it's time to import projects (= GitLab speak for "repository"). This is probably best done automated. Head to Access Tokens and generate a token with "api" scope, which you can then use with curl:

$ cat salsa-import
#!/bin/sh

set -eux

PROJECT="${1%.git}"
DESCRIPTION="$PROJECT packaging"
ALIOTH_URL="https://anonscm.debian.org/git"
ALIOTH_GROUP="collab-maint"
SALSA_URL="https://salsa.debian.org/api/v4"
SALSA_NAMESPACE="2" # 2 is "debian"
SALSA_TOKEN="yourcryptictokenhere"

curl -f "$SALSA_URL/projects?private_token=$SALSA_TOKEN" \
  --data "path=$PROJECT&namespace_id=$SALSA_NAMESPACE&description=$DESCRIPTION&import_url=$ALIOTH_URL/$ALIOTH_GROUP/$PROJECT&visibility=public"

This will create the GitLab project in the chosen namespace, and import the repository from Alioth.

To get the namespace id, use something like:

curl https://salsa.debian.org/api/v4/groups | jq . | less

Pro tip: To import a whole Alioth group to GitLab, run this on Alioth:

for f in *.git; do sh salsa-import $f; done